In detail: DIY repair of a diold welding inverter from a real master for the site my.housecope.com.
Inverter welding machines are gaining more and more popularity among master welders due to their compact size, low weight and reasonable prices. Like any other equipment, these devices can fail due to improper operation or due to design flaws. In some cases, the repair of inverter welding machines can be carried out independently by examining the inverter device, but there are breakdowns that are eliminated only at the service center.
Welding inverters, depending on the models, operate both from a household electrical network (220 V) and from a three-phase (380 V). The only thing to consider when connecting the device to a household network is its power consumption. If it exceeds the capabilities of the wiring, then the unit will not work with a sagging network.
So, the following main modules are included in the device of an inverter welding machine.
Just like diodes, transistors are installed on radiators for better heat dissipation from them. To protect the transistor unit from voltage surges, an RC filter is installed in front of it.
Below is a diagram that clearly shows the principle of operation of the welding inverter.
So, the principle of operation of this module of the welding machine is as follows. The primary rectifier of the inverter is supplied with voltage from the household electrical network or from generators, gasoline or diesel. The incoming current is alternating, but passing through the diode block, becomes permanent ... The rectified current is fed to the inverter, where it is converted back to alternating current, but with changed frequency characteristics, that is, it becomes high-frequency. Further, the high-frequency voltage is reduced by a transformer to 60-70 V with a simultaneous increase in the current strength. At the next stage, the current again enters the rectifier, where it is converted to DC, after which it is supplied to the output terminals of the unit. All current conversions controlled by a microprocessor control unit.
Video (click to play).
Modern inverters, especially those based on the IGBT module, are quite demanding on the rules of operation. This is explained by the fact that when the unit is operating, its internal modules give off a lot of heat ... Although both radiators and a fan are used to remove heat from power units and electronic boards, these measures are sometimes not enough, especially in inexpensive units. Therefore, you need to strictly follow the rules that are indicated in the instructions for the device, implying periodic shutdown of the installation for cooling.
This rule is usually referred to as the “Duty Cycle” (Duty Cycle), which is measured as a percentage. Not observing the PV, overheating of the main units of the apparatus occurs and their failure occurs. If this happens with a new unit, then this breakdown is not subject to warranty repair.
Also, if the inverter welding machine is working in dusty rooms , dust settles on its radiators and interferes with normal heat transfer, which inevitably leads to overheating and breakdown of electrical components. If it is impossible to get rid of the presence of dust in the air, it is necessary to open the inverter case more often and clean all the components of the device from accumulated dirt.
But most often inverters fail when they work at low temperatures. Breakdowns occur due to the appearance of condensation on the heated control board, as a result of which a short circuit occurs between the parts of this electronic module.
A distinctive feature of inverters is the presence of an electronic control board, therefore, only a qualified specialist can diagnose and eliminate a malfunction in this unit. ... In addition, diode bridges, transistor blocks, transformers and other parts of the electrical circuit of the apparatus can fail. To carry out diagnostics with your own hands, you need to have certain knowledge and skills in working with measuring instruments such as an oscilloscope and a multimeter.
From the above, it becomes clear that, without the necessary skills and knowledge, it is not recommended to start repairing the device, especially electronics. Otherwise, it can be completely disabled, and repairing the welding inverter will cost half the cost of a new unit.
As already mentioned, inverters fail due to external factors affecting the “vital” units of the apparatus. Also, malfunctions of the welding inverter can occur due to improper operation of the equipment or errors in its settings. The most common malfunctions or interruptions in inverter operation are as follows.
Very often, this breakdown is caused by faulty network cable apparatus. Therefore, first you need to remove the cover from the unit and ring each wire of the cable with a tester. But if everything is in order with the cable, then more serious diagnostics of the inverter will be required. Perhaps the problem lies in the standby power source of the device. The repair technique for the “duty room” using the example of a Resant brand inverter is shown in this video.
This malfunction can be caused by an incorrect setting of the amperage for a certain diameter of the electrode.
You should also consider and welding speed ... The smaller it is, the lower the current value must be set on the control panel of the unit. In addition, to match the current strength to the diameter of the additive, you can use the table below.
If the welding current is not regulated, the cause may be breakdown of the regulator or violation of the contacts of the wires connected to it. It is necessary to remove the cover of the unit and check the reliability of the connection of the conductors, and, if necessary, ring the regulator with a multimeter. If everything is in order with him, then this breakdown can be caused by a short circuit in the inductor or a malfunction of the secondary transformer, which will need to be checked with a multimeter. If a malfunction is found in these modules, they must be replaced or rewound to a specialist.
Excessive power consumption, even when the device is not loaded, most often causes turn-to-turn closure in one of the transformers. In this case, you will not be able to repair them yourself. It is necessary to take the transformer to the master for rewinding.
This happens if the voltage drops in the network ... To get rid of the sticking of the electrode to the parts to be welded, you will need to correctly select and set up the welding mode (according to the instructions for the device). Also, the voltage in the network may sag if the device is connected to an extension cord with a small wire cross-section (less than 2.5 mm 2).
It is not uncommon for a voltage drop that causes the electrode to stick when using a power strip that is too long. In this case, the problem is solved by connecting the inverter to the generator.
VIDEO If the indicator is on, this indicates overheating of the main modules of the unit. Also, the device can turn off spontaneously, which indicates tripping of thermal protection ... So that these interruptions in the operation of the unit do not occur in the future, again, it is necessary to adhere to the correct mode of the duration of the on (DC).For example, if duty cycle = 70%, then the device should work in the following mode: after 7 minutes of operation, the unit will have 3 minutes to cool down.
In fact, there can be a lot of various breakdowns and the reasons that cause them, and it is difficult to list them all. Therefore, it is better to immediately understand what algorithm is used to diagnose the welding inverter in search of faults. You can find out how the device is diagnosed by watching the following training video.
Repair of welding inverters, despite its complexity, in most cases can be done independently. And if you are well versed in the design of such devices and have an idea of what is more likely to fail in them, you can successfully optimize the costs of professional service.
Replacement of radio components in the process of repairing a welding inverter
The main purpose of any inverter is to generate a constant welding current, which is obtained by rectifying a high-frequency alternating current. The use of a high-frequency alternating current, converted by means of a special inverter module from a rectified mains supply, is due to the fact that the strength of such a current can be effectively increased to the required value using a compact transformer. It is this principle underlying the operation of the inverter that allows such equipment to have compact dimensions with high efficiency.
Functional diagram of the welding inverter
The welding inverter circuit, which determines its technical characteristics, includes the following main elements:
a primary rectifier unit, the basis of which is a diode bridge (the task of such a unit is to rectify an alternating current supplied from a standard electrical network);
an inverter unit, the main element of which is a transistor assembly (it is with the help of this unit that the direct current supplied to its input is converted into an alternating current, the frequency of which is 50–100 kHz);
a high-frequency step-down transformer, on which, due to a decrease in the input voltage, the output current is significantly increased (due to the principle of high-frequency transformation, a current can be generated at the output of such a device, the strength of which reaches 200–250 A);
output rectifier, assembled on the basis of power diodes (the task of this block of the inverter includes rectifying an alternating high-frequency current, which is necessary for performing welding work).
The welding inverter circuit contains a number of other elements that improve its operation and functionality, but the main ones are the ones listed above.
VIDEO
Repair of an inverter-type welding machine has a number of features, which is explained by the complexity of the design of such a device. Any inverter, unlike other types of welding machines, is electronic, which requires specialists involved in its maintenance and repair to have at least basic radio engineering knowledge, as well as skills in handling various measuring instruments - a voltmeter, digital multimeter, oscilloscope, etc. ...
In the process of maintenance and repair, the elements that make up the welding inverter circuit are checked. This includes transistors, diodes, resistors, zener diodes, transformer and choke devices. The peculiarity of the design of the inverter is that very often during its repair it is impossible or very difficult to determine the failure of which particular element was the cause of the malfunction.
A sign of a burnt out resistor may be a small carbon deposit on the board, which is difficult to distinguish with an inexperienced eye.
In such situations, all the details are checked sequentially.To successfully solve such a problem, it is necessary not only to be able to use measuring instruments, but also to be quite familiar with electronic circuits. If you do not have such skills and knowledge at least at the initial level, then repairing a welding inverter with your own hands can lead to even more serious damage.
Realistically assessing their strengths, knowledge and experience and deciding to undertake independent repair of inverter-type equipment, it is important not only to watch a training video on this topic, but also to carefully study the instructions, in which manufacturers list the most typical malfunctions of welding inverters, as well as ways to eliminate them.
VIDEO
Situations that can cause the inverter to fail or lead to malfunctions can be divided into two main types:
associated with the wrong choice of welding mode;
caused by the failure of parts of the device or their incorrect operation.
The technique for detecting an inverter malfunction for subsequent repair is reduced to the sequential execution of technological operations, from the simplest to the most complex. The modes in which such checks are performed and what their essence is, is usually specified in the equipment instructions.
Common inverter malfunctions, their causes and remedies
If the recommended actions did not lead to the desired results and the operation of the device has not been restored, most often this means that the cause of the malfunction should be looked for in the electronic circuit. The reasons for the failure of its blocks and individual elements may be different. Let's list the most common ones.
Moisture has penetrated into the interior of the device, which can happen if precipitation falls on the body of the device.
Dust has accumulated on the elements of the electronic circuit, which leads to a violation of their full cooling. The maximum amount of dust gets into inverters when they are used in highly dusty rooms or on construction sites. In order not to bring the equipment to such a state, its interior must be regularly cleaned.
Overheating of the elements of the electronic circuit of the inverter and, as a consequence, their failure can lead to non-observance of the duration of the switch (DC). This parameter, which must be strictly observed, is indicated in the technical passport of the equipment.
Liquid traces inside the inverter housing
The most common problems encountered when operating inverters are as follows.
Unstable arc burning or active metal spatter
This situation may indicate that the wrong amperage has been selected for welding. As you know, this parameter is selected depending on the type and diameter of the electrode, as well as on the speed of welding. If the packaging of the electrodes that you are using does not contain recommendations on the optimal value of the current strength, you can calculate it using a simple formula: 1 mm of the electrode diameter should account for 20–40 A of welding current. It should also be borne in mind that the lower the welding speed, the lower the current should be.
Dependence of the diameter of the electrodes on the strength of the welding current
This problem can be associated with a number of reasons, and most of them are based on undervoltage. Modern models of inverter devices also operate at reduced voltage, but when its value drops below the minimum value for which the equipment is designed, the electrode begins to stick. A drop in the voltage value at the output of the equipment can occur if the device blocks do not contact the panel sockets poorly.
This reason can be eliminated very simply: by cleaning the contact sockets and fixing the electronic boards in them more tightly. If the wire through which the inverter is connected to the mains has a cross-section of less than 2.5 mm2, this can also lead to a voltage drop at the input of the device. This is guaranteed to happen even if such a wire is too long.
If the length of the supply wire exceeds 40 meters, it is practically impossible to use an inverter for welding, which will be connected with its help. The voltage in the supply circuit can also drop if its contacts are burnt or oxidized. A frequent cause of electrode sticking is insufficiently high-quality preparation of the surfaces of the parts to be welded, which must be thoroughly cleaned not only from the existing contaminants, but also from the oxide film.
Selection of the cross-section of the welding cable
This situation often occurs in the event of overheating of the inverter device. At the same time, the control indicator on the panel of the device should light up. If the glow of the latter is hardly noticeable, and the inverter does not have a sound alert function, then the welder may simply not be aware of overheating. This state of the welding inverter is also typical when the welding wires are broken or spontaneously disconnected.
Spontaneous shutdown of the inverter during welding
Most often, this situation occurs when the supply of the supply voltage is turned off by circuit breakers whose operating parameters are incorrectly selected. When working with an inverter device, automatic machines designed for a current of at least 25 A must be installed in the electrical panel.
VIDEO
Most likely, this situation indicates that the voltage in the power supply network is too low.
Automatic shutdown of the inverter during prolonged welding
Most modern inverter machines are equipped with temperature sensors that automatically turn off the equipment when the temperature in its interior rises to a critical level. There is only one way out of this situation: give the welding machine a rest for 20-30 minutes, during which it will cool down.
If after testing it becomes clear that the cause of malfunctions in the operation of the inverter device lies in its inner part, you should disassemble the case and start examining the electronic filling. It is possible that the reason lies in poor-quality soldering of device parts or poorly connected wires.
A close inspection of the electronic circuits will reveal faulty parts that may be darkened, cracked, bloated, or have burnt contacts.
Burnt parts on the Fubac IN-160 inverter board (AC-DC regulator, 2NK90 transistor, 47 ohm resistor)
During repair, such parts must be removed from the boards (it is advisable to use a soldering iron with a suction for this), and then replaced with similar ones. If the marking on the defective elements is not readable, then special tables can be used to select them. After replacing defective parts, it is advisable to test the electronic boards using a tester. Moreover, this must be done if the inspection did not reveal the elements to be repaired.
A visual check of the electronic circuits of the inverter and their analysis with a tester should start with the power unit with transistors, since it is he who is the most vulnerable. If the transistors are faulty, then, most likely, the circuit that shakes them (driver) has also failed. The elements that make up such a circuit must also be checked first.
After checking the transistor unit, all other units are checked, for which a tester is also used. The surface of the printed circuit boards must be carefully examined to determine the presence of burnt areas and breaks on them.If any are found, then such places should be carefully cleaned and jumpers should be soldered on them.
If burnt or broken wires are found in the filling of the inverter, then during repair they must be replaced with similar ones in cross section. Although the diode bridges of the inverter rectifiers are reliable enough, they should also be ringed with a tester.
VIDEO
The most complex element of the inverter is the key control board, the operability of which depends on the operability of the entire device. Such a board for the presence of control signals that are fed to the gate buses of the key block is checked using an oscilloscope. The final stage in testing and repairing the electronic circuits of the inverter device should be to check the contacts of all existing connectors and clean them with a regular eraser.
Self-repair of an electronic device such as an inverter is quite difficult. It is almost impossible to learn how to repair this equipment just by watching a training video, for this you need to have certain knowledge and skills. If you have such knowledge and skills, then watching such a video will give you the opportunity to make up for the lack of experience.
VIDEO
When buying an inverter welding machine for working in a garage or in the country, the first thought is - wow, now I’ll cook everything! No need for a welder's diploma, the device is designed for a user without special education. Welding is now easier and more comfortable to handle. The main thing is to understand the principle of work and first aid in case of difficulties and breakdowns.
Since the early 2000s, inverter welders have become cheaper and more affordable. To carry out welding at home, it is enough to have this small and easy-to-use device and good electrodes.
Inverter machines are lightweight, compact, and their scope of use and welding quality are higher than those of heavy and bulky welding transformers. They fulfill their task in full: they cook cars, gates, pipe structures (for example, greenhouses or gazebos). Working with them is mobile - throwing a sliding belt over your shoulder, welding is carried out in any hard-to-reach places.
With vertical, horizontal or top welding, the current is reduced by 10–20%, and when welding at an angle, it is increased by the same amount compared to the normal position.
There are also no problems with the connection, the welding machine works from a normal electrical network. It is great that it will not stop when the mains voltage drops. If the deviation is within +/- 15%, the device will continue to work normally. The current value can be adjusted by selecting the power depending on the type and thickness of the metal. All this makes inverters ideal for beginners and professionals alike.
VIDEO
The inverter machine connects parts with direct current using electric arc welding with a coated electrode. A big plus is that at the very beginning of the process there are no power surges in the network to which the device is connected. The storage capacitor ensures the continuity of the electrical circuit and soft ignition of the arc with its further automatic maintenance. When connected to an electrical outlet, the 50 Hz AC mains voltage is converted first into a DC voltage and then into a high-frequency modulated voltage. Then, with the help of a high-frequency transformer, the current increases, the voltage decreases, and the output current is rectified. The device provides for the adjustment of the welding current and protection against overheating.
The basic operating mode of inverter welding machines is MMA. This is manual arc welding with stick electrodes. For welding steel and cast iron products on direct or alternating current, a diameter of 1.6–5.0 mm is used.
Devices differ in power and duration of the working cycle ... The second indicator is the period during which it is allowed to cook at the maximum permissible power in order to prevent the device from overheating. It is denoted by the letters PV (on period) and is determined as a percentage relative to a unit of time of 10 minutes. For example, if the PV of 60% is indicated on the device, this means that it can be cooked for 6 minutes, and then turned off for 4 minutes. Sometimes the welding cycle is set to 5 minutes. Then the value of the PV indicator of 60% indicates the period of work in 3, and rest in 2 minutes. Indicators of PV and duty cycle are indicated in the instructions for each device.
In order not to look for a repair specialist at the first difficulties in the operation of the device, it is advisable to have at least a basic understanding of its design.
Craftsmen with knowledge of electrical engineering assemble the welding machine themselves. Not only for the sake of economy, but also at the behest of the creative soul. Circuit diagrams of inverters, drawings and instructions of those who made the inverter themselves are posted on the Internet. The main thing is to get stability of the welding arc. Most often, the "oblique bridge" scheme ("Barmaley's circuit") is used using two key transistors: bipolar or field-effect. They are placed on a radiator to dissipate heat, they open and close synchronously.
The electrical design of the circuit eliminates high-voltage emissions and allows the use of relatively low-level switches. The scheme is used because of its simplicity, reliability and not very expensive consumables.
VIDEO
The apparatus is assembled from the following blocks:
power supply for stabilization of input signals. A metal partition is placed between it and other elements and blocks. The multiwinding inductor is controlled by transistors and a stored energy capacitor. Diodes are used in the throttle control system;
a power unit, with the participation of which a complete current conversion cycle takes place. Collected from a primary rectifier, an inverter transistor converter, a high-frequency step-down transformer and an output rectifier;
Control block. It is based on a master oscillator with a special microcircuit or a pulse-width modulator. They put a resonant choke and 6-10 resonant capacitors;
protective block. Most often they are assembled on a power unit, installing thermal switches for thermal protection of its elements. To avoid overloads, they put a board based on the 561LA7 microcircuit. Snubbers with resistors and capacitors K78-2 protect the converter and rectifiers.
VIDEO
The design of inverter welding machines is more complicated than transformer ones and, unfortunately, less reliable. This often leads to the failure of various nodes for the following reasons:
low protection against dust. When it accumulates inside, a thermal protection signal is triggered, the device turns off. Disassembly is required at least twice a year to clean the internal parts with a jet of compressed air or a soft brush;
ingress of moisture inside, causing a short circuit, dangerous for the unit;
low quality of the cooling system in cheap devices. Because of this, the plastic parts of the structure melt, the emergency shutdown does not work. In models with tunnel ventilation, the radiator is located along the case, and the main components are located inside it. Such devices are much more expensive;
voltage surges, especially a drop to 190 V or more;
overload when cutting thick metal and work for which the specific device is not designed. Then the IGBT power module fails;
poor-quality fastening in the contacts of the pads, which provokes overheating of these places and sparking;
sensitivity to shocks and falls due to the presence of plastic parts;
poor quality of spare parts that are used for repairs;
violation of the permissible temperature regime.Electronic microprocessors melt and degrade when overheated. It is recommended to adhere to the range from -10 to +40 o C.
Malfunctions are both mechanical and associated with the failure of electronics. The welding machine is a complex device, problems can arise anywhere:
A short circuit or breakdown in any important node of the electrical circuit makes it impossible to operate the welding machine:
a malfunction of the control board does not give a stable welding current and does not allow a normal arc to be obtained;
damage to the transistor of the upper printed circuit board leads to the shutdown of the device;
failure of the overheating protection system is determined by the smell of burnt insulation, smoke comes from inside the case.
When starting to repair a faulty unit, it is worth considering some points.
The poor quality of the device does not always mean an internal breakdown. Wet or poor quality electrodes are often the culprit. If drying or replacing does not produce a beautiful seam, consider other possible reasons:
It is important to select the correct size of the electrodes for the correct operation of the welding machine.
To be able to repair the welding machine yourself, you first need to deal with its internal structure. On the front panel there are sockets for working cables, a knob for the current regulator and a power indicator. If the design provides for additional functions, the operating indicators are located here.
The check begins with an external examination of the device. The first step is to check for mechanical damage. If there are black spots on the case, most likely a short circuit has occurred. The tester checks the fuses, replace them if necessary, inspect the insulation of the welding cables, the connections in the sockets. If necessary, tighten the bolts, clean the contacts.
After unscrewing the screws and removing the cover, the inside of the machine opens, where the following components are located:
power transistor board;
control board;
rectifier diode board;
mains voltage rectification board;
fan;
controls - knob and switches.
The following tools are required for repairs.
Multimeter with multiple modes:
ringing the chain;
ringing diodes;
voltage measurement;
resistance test.
Oscilloscope. It is used to test diodes, zener diodes, transistors, capacitors and other elements of an electrical circuit. Repairing a welding machine is much more difficult without an oscilloscope.
The filling of the welding machine is understandable for those who work with radio electronics. If the necessary skills are not available in this area, the intervention will only harm. Without knowing the rules for handling the board and the technology of such delicate work, you can cause much more damage than the initial one. It is cheaper and safer to entrust the repair to a professional.
If it is difficult to find a specialized workshop, you have to restore the welding inverter yourself. Important check in sequence what stopped the operation of the device.
If difficulties arise, read the operating instructions for the welding machine first. It necessarily contains a section on possible problems during welding, causes of malfunctions and recommendations for their elimination.
After removing the cover of the device, there is often a noticeable violation of the soldering of parts, swelling of capacitors, breakage of contacts. In such cases, the damaged parts are replaced with similar ones. Torn off and burnt areas are removed and re-soldered. If it is not possible to quickly determine the cause of the breakdown, check each element of the electrical circuit. Diodes, transistors, zener diodes, resistors and other parts are tested.
A detailed check is carried out sequentially: from the parts that most often fail to the most resistant ones.
Unplug the device from the socket before checking the power supply!
For self-repair, craftsmen use phosphoric acid. If you need to solder something to the diode cases (for example, broken off racks), they are pre-tinned. When repairing a broken-off rack, take into account the perpendicularity. It is important to install it by clearly aligning the holes. If you solder, even with a minimal skew, the post will break again when you tighten the fastener again.
If there is no technical hair dryer, a 100–150 W soldering iron is used for desoldering. This will not damage the connectors and tracks. Experts recommend, for a better result, before soldering, heat the block to 160–170 ° C, while the plastic parts of the fan should not be heated. When working with a soldering iron or other heating elements, care must be taken not to touch the fusible parts of the apparatus.
VIDEO
The inverter welding machine is confidently registered in home workshops. Before buying, it is worth taking the time to learn the basics of welding and electrical engineering. This will help you navigate the characteristics of the device and, if necessary, repair it yourself. It is better to entrust difficult cases to specialists.
It is well known that the repair of welding machines in the overwhelming majority of cases can be organized and carried out independently. The only exception is the restoration of the efficiency of the electronic inverter, the complexity of the circuit of which does not allow for full repairs at home.
Even an electrical engineer can be confused by just trying to turn off the protection of an inverter. So in this case, it is best to seek help from a specialized workshop.
the device does not turn on when connected to the mains and started;
sticking of the electrode with a simultaneous hum in the area of the converter;
spontaneous shutdown of the welding machine in case of overheating.
Repair always begins with an inspection of the welding machine, checking the supply voltage. It is not difficult to repair transformer welding machines, moreover, they are not picky to maintain. In inverter devices, it is more difficult to determine the breakdown, and repair at home is often impossible.
However, if handled correctly, inverters will last a long time and will not break down. Protect from dust, high humidity, frost, store in a dry place. There are the most typical malfunctions of welding machines, which can be eliminated by hand.
In this case, first of all, you need to make sure that there is voltage in the network and the integrity of the fuses installed in the transformer windings. If they are working properly, use the tester to ring the current windings and each of the rectifier diodes, thereby checking their performance.
Sometimes the filter capacitor fails. In this case, the repair will consist in checking it and replacing it with a new part.
If all the elements of the circuit are working properly, it is necessary to deal with the mains voltage, which can be greatly underestimated and is simply not enough for the normal functioning of the welding machine.
Electrode sticking and arc interruption can be caused by a voltage drop due to a short circuit in the transformer windings, diode failure, or loose connection contacts. A breakdown of the capacitor filter or short circuiting of individual parts to the body of the welding machine is also possible.
If sticking is accompanied by a strong hum of the transformer, this also indicates an overload in the load circuits of the device or a short circuit in the welding wires.
One of the repair options with the elimination of these effects can be the restoration of the insulation of the connecting cables, as well as the tightening of loose contacts and terminal blocks.
In some cases, repairs can be carried out independently if the device starts to shut down spontaneously. Most models of welding machines are equipped with a protective circuit (automatic) that is triggered in a critical situation, accompanied by a deviation from normal operation. One of the options for such protection involves blocking the operation of the device when the ventilation module is turned off.
After spontaneous shutdown of the welding machine, first of all, you should check the state of protection and try to return this element to working condition. .
If the protective unit re-operates, it is necessary to proceed to troubleshooting according to one of the methods described above, associated with short circuits or malfunction of individual parts.
In this situation, first of all, you should make sure that the cooling unit of the unit is working properly, and that overheating of the internal spaces is excluded.
In the absence of internal protection, the circuit breaker can be installed in the electrical panel. To maintain the normal functioning of the welding unit, its settings must correspond to the selected modes.
So, some models of such machines (welding inverter, in particular), in accordance with the instructions, should work according to a schedule that assumes a break for 3-4 minutes after 7-8 minutes of continuous welding.
Before repairing an inverter welding machine with your own hands, it is advisable to familiarize yourself with the principle of operation, as well as with its electronic circuit. Their knowledge will allow you to quickly identify the causes of breakdowns and try to eliminate them in a timely manner.
The use of an intermediate high-frequency signal makes it possible to obtain a compact impulse device that has the ability to effectively adjust the value of the output current.
Breakdowns of all welding inverters can be conditionally divided into the following types:
malfunctions associated with errors in the choice of the welding mode;
failures in operation due to the failure of the electronic (conversion) module or other parts of the device.
The method for detecting inverter malfunctions associated with malfunctions of the circuit involves the sequential execution of operations performed according to the principle "from simple damage to more complex breakdown." The nature and cause of breakdowns, as well as repair methods, can be found in more detail in the summary table.
It also contains data on the main parameters of welding, providing a trouble-free (without turning off the inverter) operation of the device.
VIDEO
Maintenance and repair of inverter-type welding machines is distinguished by a number of features associated with the complexity of the circuitry of these electronic units. To repair them, you will need certain knowledge, as well as the ability to handle measuring instruments such as a digital multimeter, an oscilloscope, and the like.
In the process of repairing an electronic circuit, first, a visual inspection of the boards is carried out in order to identify burnt or "suspicious" elements in the composition of individual functional modules.
If during the inspection no violations can be found, the troubleshooting continues by detecting violations in the operation of the electronic circuit (checking the voltage levels and the presence of a signal at its control points).
To do this, you will need an oscilloscope and a multimeter, which you should start working with only if you have full confidence in your abilities. If you have any doubts about your qualifications, the only correct solution would be to take (carry) the device to a specialized workshop.
Specialists in the repair of complex impulse devices will quickly find and eliminate the malfunction that has arisen, and at the same time will carry out maintenance of this unit.
If you decide to repair the board yourself, we recommend using the following advice from experienced specialists.
If burnt wires and parts are found during a visual inspection, they should be replaced with new ones, and at the same time all connectors should be plugged in, which will eliminate the option of losing contact in them.
To do this, it is necessary to find sources in which the diagrams of voltages and currents are given, intended for a more complete understanding of the operation of this unit.
Based on these diagrams using an oscilloscope, you can sequentially check all the electronic circuits and identify the node in which the normal picture of the signal conversion is disturbed.
One of the most complex components of an inverter welding machine is considered to be an electronic key control board, which can be checked for serviceability using the same oscilloscope.
If you have doubts about the performance of this board, you can try to replace it with a serviceable one (from another working inverter) and try to start the welding machine again.
In case of a favorable outcome, it remains only to give your board for repair or replace it with a purchased new one. The same should be done when there is a suspicion that all other modules or blocks of the welding machine are in good working order.
VIDEO
In conclusion, we recall that the repair of any welding units (and inverters, in particular) is considered a rather complex procedure that requires certain skills and ability to handle complex measuring equipment.
Video (click to play).
If you have the slightest doubt about your professionalism, you should use the help of specialists and give them the opportunity to return the faulty device to work.
